OverDrive Issue

[jmray91]

How do you fix the overdrive in 2001 Alero 2.4L DOHC?

[a.graham52]

what is wrong with the overdrive?

[jmray91]

well its takes like 5 to 6 seconds for overdrive to take effect and when it does it slams my car forward.

[a.graham52]

overdrive is just a gear ratio. nothing more then that. is your slam caused when the torque converter enguages? os it slaming in all gears? ses light on? hows your fluid level?

[jmray91]

yeah after it changes gears it slams no lights on and all fluid levels good.

[a.graham52]

tried disconnecting the battery for half an hour? that will wipe out shift adapts. maybe a quick fix?

[jmray91]

na tried that it doesnt help any at all.

[zzyzzx]

Did you check for codes? I would, but mostly because it's easy enough to do.

How many miles are on this transmission?

Are you sure it's the OD gear and not the torque converter?

When was the last time you changed the fluid and filter?

Did you check the TPS?

http://en.wikipedia.org/wiki/Transmission_control_unit#Throttle_position_sensor _.28TPS.29

Throttle position sensor (TPS)

The TPS sensor along with the vehicle speed sensor are the two main inputs for most TCUs. Older transmissions use this to determine engine load, with the introduction of drive-by-wire technology, this is often a shared input between the ECU and TCU. The input is used to determine the optimum time and characteristics for a gear change according to load on the engine. The rate of change is used to determine whether a downshift is appropriate for overtaking, for example, the value of the TPS is also continually monitored during the journey and shift programmes are changed accordingly (economy, sport mode, etc.). The TCU can also reference this information with the vehicle speed sensor to determine vehicle acceleration and compare this with a nominal value; if the actual value is much higher or lower (such as driving uphill or towing a trailer) the transmission will change its gearshift patterns to suit the situation.

Off hand I an suspicious of the transmission oil pressure at highway RPM's.

[a.graham52]

this is true... bad tps can make the trans shift wierd.

[Nate's Alero]

So can a bad IAT. Check both of them. Also, the "slamming" could be the Tourque converter locking up to save gas. Sounds like bad IAT to me...

[jmray91]

There are no codes. Tranny has 100,000 miles. How do you check the overdrive gear and torque converter? Easy to replace? Cost? Changed the fluid and filter already. Had it flushed around 99,000 miles. TPS is brand new. IAT is brand new as well

[zzyzzx]

Easy to replace? Cost?

No!

Were any of your new parts made in China?

Anyway, I suspect that you have issues with the solenoid that makes the lockup on the torque converter work OR you have transmission oil pressure problems at high RPM's. Neither should require you to remove the transmission, it's a control problem, or maybe you used the wrong transmission fluid when you changed it.

[jmray91]

trans fluid is dex 5 i think whatever the tsb states for tranny fluid. New parts either us canada or mexico. how do you fix the solenoid?

[mmorello82]

Ooh ooh! I know whats wrong!! Mine did it with two used tranny's before I put a reman in it. It is the pressure control Solenoid. It is packed in there with the clutches. What I was told is the o-ring around it goes bad and will not allow proper fluid pressure. And to remove it is a complete tranny dis-assemble. Sorry man, that's why I bought a reman

[zzyzzx]

It is the pressure control Solenoid. It is packed in there with the clutches. What I was told is the o-ring around it goes bad and will not allow proper fluid pressure.

Umm, I have never seen or heard of one where the solenoids are in with the clutch bands. Normally they are on the valve body, and on newer transmissions they are all accessible just by removing the transmission pan. I would want to verify this, since transmission shops are pathological liars and want to sell you a new transmission when you only need a solenoid or an O ring.

[mmorello82]

I have a exploded view of the 4T40E and 4T45E that shows it packed in there

[zzyzzx]

I have a exploded view of the 4T40E and 4T45E that shows it packed in there

I have seen them on top of the valve body, but it's still serviceable by removing the pan, then valve body, then (with the valve body on a bench) replace solenoid. Then reinstall. But seeing one just in the middle of the transmission like you say makes no sense. I'll have to check my factory service manual.

Are you sure that this isn't how it's done:
http://www.domesticcrew.com/tony/TCCreplacement.pdf

I would so some reading here as well:
http://www.saturnfans.com/forums/archive/index.php/t-128100.html

[AleroB888]

I have seen them on top of the valve body, but it's still serviceable by removing the pan............Are you sure that this isn't how it's done:
http://www.domesticcrew.com/tony/TCCreplacement.pdf

It says remove the side cover.

[zzyzzx]

Yeah, but it says nothing about how hard it is to remove the side cover. On some other cars, it's a matter of removing a wheel and a fender inner liner. Some cars you will have to remove more than that, like a strut.

http://www.justanswer.com/oldsmobile/4d6n9-olds-alero-code-po742-fix.html

Or just go here:
http://www.grandamgt.com/forum/showthread.php?t=28893

Says remove ball joint, axle, inner fender, air cleaner, and a couple of mounts. Not easy, but doable. From what I can tell, you can do this with the transmission in the car.